There is a great need for convenient, cost effective techniques to securely handle and deliver documents and other items. Existing methods such as express and personal couriers, registered mail, facsimile and electronic mail fulfill some of these needs but these techniques each have their problems and are deficient in important ways.
Trusted Personal Couriers
Perhaps the ultimate in secure document handling is the personal trusted courier. Many of us have seen spy films showing a trusted courier delivering documents containing state secrets. In such scenarios, the document sender places the document or other item into a lockable attaché case. The sender seals and locks the case with a key or combination that only he and the recipient have. The courier handcuffs the case to his or her wrist, boards an airplane and flies to the required destination—all the while carefully guarding the attaché case and its contents. Upon arriving at the destination, the courier personally delivers the case to the intended recipient. The recipient unlocks the case and retrieves its contents, all the while having a high degree of assurance that the contents have been kept secret.
The confidentiality, security and reliability provided by a personal trusted document courier has never really been matched by any other form of document delivery. Even though we sometimes might want or need the services of a personal trusted document courier, it is likely that practical reasons (such as cost and availability) require us to use less trusted forms of delivery for even our most important and confidential documents or other items. Moreover, even the trusted courier technique does not provide a reliable means of later providing how and when the information was used by the recipient and/or subsequently handled by others to whom the recipient may pass the information and what information was actually sent. This approach also cannot provide the degree of interactivity between the sender and the recipient possible in a world of near instantaneous communications, including seamlessly supporting processes related to rights management, and document creation and dissemination.
As discussed below, existing alternatives to the trusted courier are more practical and less expensive, and some offer advantages such as instantaneous communications and interactivity—but all suffer from various disadvantages.
Express Courier Services
Federal Express and other express courier services provide rapid (for example, overnight) delivery services at a relatively high degree of trustedness.
In the typical case, the sender places the items to be delivered into a special, tear resistant sealed envelope, and fills out an “air bill” that lists the sender's name, address and telephone number, and the intended recipient's name, address and telephone number. The “air bill” also lists options such as, for example, the type of delivery service required (i.e., delivery next business morning, next business afternoon, or second business day), whether the sender requires Federal Express to obtain the recipient's signature, the payment method, and a unique “tracking number” used to uniquely identify the package.
Once the package is complete and ready to send, the sender may provide it to Federal Express through a number of different methods:                the sender may take the package to a Federal Express office and personally hand it to a clerk,        the sender may drop the completed envelope in any one of many pervasive Federal Express drop off boxes, and someone will come and collect the envelopes from the boxes sometime before the end of the business day and deliver them to a Federal Express office, or        the sender can call Federal Express and arrange for a delivery person to come and pick up the package.        
Federal Express maintains a fleet of aircraft that shuttle most packages to a central sorting and routing facility for subsequent dispatch to various destinations across the United States and the world. A fleet of delivery trucks deliver the packages from local airports to each recipient. At the sender's option, a delivery person may obtain a recipient's signature at the time she delivers the package—providing documentation that may later be used to prove the package was in fact received by the intended recipient or someone at his or her home or office.
Federal Express uses automated computer tracking and package handling equipment to route individual packages to their destinations. Delivery information is put into the tracking computer to allow customers and service people to automatically retrieve information about when and to whom particular packages were actually delivered, or where the package happens to be at the moment.
Federal Express and other similar document delivery services have been highly successful because they cost-effectively ensure reliable delivery of original documents and other items. Nevertheless, they do have some significant disadvantages and limitations. For example:                They are much more expensive than other delivery mechanisms at least in part because of the high labor, transportation, and infrastructure (many offices, planes, etc.) costs involved.        They do not provide the very high degree of confidentiality desired for certain confidential business or other documents.        They generally can only reliably verify that the package was delivered to the intended recipient (or his or her home or place of business)—and not that the intended recipient opened the package or read or saw or used the document.        The one (or two) day delay they introduce may be too great for time sensitive or time pressing items.        
These problems are exacerbated when several individuals and/or organizations in different geographical locations are all parties to a transaction—a complex, multiparty contract, for example—and all must sign or otherwise process and/or execute one or more related documents.
Registered Mail
A relatively more secure delivery technique is registered mail. Registered mail correspondents can have a high degree of confidence that their packages will arrive at their required destinations—but may not like the time delays and additional expense associated with this special form of mail handling.
To use registered mail, the sender places her document or other items into a sealed envelope or package and takes her package to the nearest Post Office. For security, the Post Office may prohibit the use of resealable tape and mailing labels, and instead require the package to be sealed with paper tape and the address to be written directly on the package. These safeguards help to ensure that any attempts to tamper with the package or its contents will be detected.
The Post Office securely transports the registered mail package to the recipient, requiring each postal employee who accepts custody of the package along its journey to sign and time stamp a custody record. The postal carrier at the recipient's end personally delivers the package to the recipient—who also has to sign for it and may be asked to produce proof of identification. The custody record establishes a chain of custody, listing every person who has had custody of the package on its journey from sender to recipient.
As discussed above, registered mail is relatively secure and confidential but delivery takes a long time and is very labor and infrastructure intensive.
Facsimile
Facsimile is an electronic-based technology that provides virtually instantaneous document delivery. A facsimile machine typically includes a document scanner, a document printer, and electronic circuits that convert document images to and from a form in which they can be sent over a telephone line. Facsimile requires each of the sender and the intended recipient to have a facsimile machine. The sender typically places the document to be sent into a document feeder attached to a facsimile machine. The sender then typically keys in the telephone number of the intended recipient's facsimile machine and presses a “start” button. The sender's facsimile machine automatically dials and establishes contact with the recipient's facsimile machine.
Once a good connection is established, the sender's facsimile machine begins to optically scan the document one page at a time and convert it into digital information bits. The sender's facsimile machine converts the digital bits into a form that can be transmitted over a telephone line, and sends the bits to the intended recipient's facsimile machine. The sender's facsimile machine may also send as part of the document, a “header” on the top of each page stating the sender's identity, the page number of the transmission, and the transmission time. However, these headers can be changed at will by the sender and therefore cannot be trusted.
Since the recipient's facsimile machine receives the transmitted information at the same time the sender's facsimile machine is sending it, delivery is virtually instantaneous. However, sending a document to an unattended facsimile machine in an insecure location may result in the document falling into the wrong hands. Another common scenario is that the facsimile machine operator, through human error, dials the wrong telephone number and ends up delivering a confidential document to the wrong person (for example, the local grocery store down the street, or in some unfortunate cases, the opposing side of a negotiation, legal proceeding or other pitched battle). Thousands of faxes are lost every day in a “black hole”—never arriving at their desired destinations but possibly arriving at completely different destinations instead.                Some secure facsimile machines such as those used by government and military organizations, or by companies needing a significantly higher level of security provide an extra security/authentication step to ensure that the intended recipient is physically present at the receiving facsimile machine before the sender's machine will transmit the document. In addition, it is possible to use encryption to prevent the facsimile transmitted information from being understood by electronic eavesdroppers. However, such specially equipped facsimile machines tend to be very expensive and are not generally available for common commercial facsimile traffic. Moreover, facsimile machines typically can send and receive documents only—and therefore are not very versatile. They do not, for example, handle digital items such as audio, video, multimedia, and executables, yet these are increasingly part and parcel of communications for commerce and other purposes. Thus, despite its many advantages, facsimile transmissions do not provide the very high degree of trustedness and confidence required by extremely confidential documents, nor do they provide the degree of flexibility required by modern digital communications. As with Express Courier Services and Registered Mail, faxing can only indicate that the package was delivered to the intended recipient (or his or her home or place of business)—and not that the intended recipient opened the package or read or saw or used the document.Electronic Mail        
More and more, people are using electronic mail to send documents, messages, and/or other digital items. The “Internet explosion” has connected millions of new users to the Internet. Whereas Internet electronic mail was previously restricted primarily to the academic world, most corporations and computer-savvy individuals can now correspond regularly over the Internet.
Currently, Internet electronic mail provides great advantages in terms of timeliness (nearly instantaneous delivery) and flexibility (any type of digital information can be sent), but suffers from an inherent lack of security and trustedness. Internet messages must typically pass through a number of different computers to get from sender to recipient, regardless of whether these computers are located within a single company on an “Intranet” for example, or on Internet attached computers belonging to a multitude of organizations. Unfortunately, any one of those computers can potentially intercept the message and/or keep a copy of it. Moreover, even though some of these systems have limited “return receipt” capabilities, the message carrying the receipt suffers from the same security and reliability problems as the original message.
Cryptography (a special mathematical-based technique for keeping messages secret and authenticating messages) is now beginning to be used to prevent eavesdroppers from reading intercepted messages, but the widespread use of such cryptography techniques alone will not solve electronic mail's inherent lack of trustedness. These electronic mail messages, documents and other items (e.g., executable computer programs or program fragments) that might have been sent with them as “attachments,” remain vulnerable to tampering and other unauthorized operations and uses once decrypted and while delivery may be reported, actual use can not be demonstrated. Some people have tried to develop “privacy enhanced” electronic mail, but prior systems have only provided limited improvements in reliability, efficiency and/or security.